Will I start receiving SREC payments as soon as I generate the electricity?

No. There will be a delay (from six months to over a year) between electricity generation and payment for SRECS.
SRECS are “minted” on the fifteenth day of the first month after the quarter in which they are generated. But they cannot be sold at auction for another quarter. So if you finish generating 1 MWh in the second quarter, they can not be auctioned until October, (perhaps even later if the market doesn’t clear). But once you start receiving payments, they should come at regular intervals.